The present invention relates to a method and device for preliminary testing of a serum sample in a sample container. The present invention is particularly useful for establishing a hemolytic index, an icteric index and a lipemic index for a neat serum sample, prior to removing the neat serum sample from the primary collection tube. The present invention is also useful for evaluating whether sufficient serum sample is present in the primary collection tube.
The accurate analysis of a serum sample is often instrumental in determining the health of a patient and what measures are necessary to restore the health of the patient. In an effort to reduce laboratory labor costs, many hospitals and laboratories utilize automated clinical analyzers to analyze patient serum samples. Clinical analyzers are presently able to accurately and quickly perform such functions as drug monitoring, specific protein blood analysis and cancer detection on a serum sample.
These clinical analyzers commonly utilize a plurality of cuvettes which are sequentially subjected to a variety of tests during a machine cycle of the clinical analyzer. Typically, during a machine cycle, the testing begins at one location, samples are added at one location and multiple serum samples are sequentially tested.
In some cases, the integrity of the serum sample may affect the interpretation of the results of the clinical analyzer. For example, preanalytical variables in the serum sample, which are not related to the patient disease state, may cause a different interpretation of the condition of the patient. Preanalytical variables include hemolysis (ruptured red blood cells), Icteris (excessive Bilirubin) and Lipemia (high, visible lipid content).
One way to evaluate the integrity of the serum sample is to have a skilled laboratory worker visually inspect the color of the serum sample. A normal serum sample has a light yellow to light amber color. Alternately, a serum sample containing Hemolysis is reddish in color, a sample containing Icteris is dark yellow/brown in color and a sample containing Lipemia is whitish in color. Thus, the degree of red color in a serum sample corresponds to the amount Hemolysis present in the serum sample, the degree of dark yellow/brown color corresponds to the amount of Icteris present in the serum sample and the degree of whitish color corresponds to the amount of Lipemia present in the serum sample.
Typically, a laboratory worker will assign an hemolytic index, an icteric index and a lipemic index to the serum sample based upon the color. Based upon the value of the hemolytic index, the icteric index and the lipemic index, the interpretation of the results from the clinical analyzer can be evaluated. Alternately, if the value of one or more of the hemolytic index, the icteric index and the lipemic index are too high, the serum sample will be discarded without analysis by the clinical analyzer.
However, visual inspection can be labor intensive and costly. Further, the possibility of human error exists with visual inspection, the results of the visual inspection is highly subjective and varies between workers, and one of the variables could mask or hide the other variables. Furthermore, with closed container sampling, bar code labels directly on the container, and automated clinical analyzers, the laboratory worker, in many instances simply does not have an opportunity to visually observe the serum sample. Thus, it is becoming increasing important to evaluate the integrity of the serum sample without the use of visual inspection by a laboratory worker.
One attempt to solve this problem involves optically viewing the serum sample after the serum sample has been transferred to one of the cuvettes of the clinical analyzer. Measuring the optical characteristics of the sample in the clinical analyzer eliminates the need for visual inspection. However, this test utilizes machine time of the clinical analyzer and if the integrity of the serum sample is determined to be compromised, additional machine time and a machine cycle are wasted. Further, this procedure can not be used with clinical analyzers which add reagents to the cuvette prior to adding the serum sample.
Another attempt to solve the problem involves separately testing a portion of the serum sample in a separate cuvette of the clinical analyzer, simultaneously with the other tests being performed on the serum sample by the clinical analyzer. However, this requires the use of a portion of the sample and the clinical analyzer. Therefore, this procedure will waste sample and machine time. Further, with this procedure, if the serum sample is determined to be compromised, a machine cycle and reagents are wasted.
Yet another attempt to solve the problem involves evaluating the serum sample in a probe during the transfer of the serum sample. This device is discussed in detail in U.S. Pat. No. 5,734,468, issued to McNeal, the contents of which are incorporated herein by reference. Unfortunately, because the integrity of the sample is evaluated in the probe, the probe must be washed with a wash fluid to prevent carry-over between serum samples. For large scale operations, the wash fluid poses several problems, including increased costs and increased environmental concerns.
In light of the above, it is an object of the present invention to provide a method and device which evaluates the integrity of a serum sample, without visual inspection by a laboratory worker. Another object of the present invention is to provide a method and device which quickly and accurately determines the presence of Hemolysis, Icteris and Lipemia in a sample, without consuming any sample and without adversely effecting the integrity of the sample. Yet another object of the present invention is to provide a method and device which establishes a hemolytic index, an icteric index and a lipemic index for the serum sample, without wasting machine time of the clinical analyzer and without interrupting the operation of the clinical analyzer. Yet another object of the present invention is to provide a method and device which determines the presence of any interferant in the sample, without consuming the sample. Still another object of the present invention is to provide a method and device which evaluates the integrity of the sample and transfers the sample to an appropriate location based upon the integrity of the sample. Yet another object of the present invention is to provide a device and method for determining the amount of sample in the sample container available for testing with the clinical analyzer.
The present invention is directed to a method and device for performing preliminary tests on a sample in a sample container which satisfies these objectives. The method includes the steps of (i) providing an optical probe; and (ii) monitoring the sample in the storage container with the optical probe to determine the suitability of the sample for additional testing. The present invention is particularly suited for performing preliminary tests on a neat serum sample in a primary collection tube without removing the neat serum sample from the primary collection tube.
The preliminary tests include a screening test to evaluate the integrity of the sample in the sample container and/or a volume test to measure the amount of sample available for testing. Importantly, with the present invention, the sample is preliminarily tested in the storage container, prior to being removed from the storage container and prior to being transferred to a clinical analyzer. Therefore, machine time of the clinical analyzer is not wasted, the sample is not consumed or altered and the sample can be transferred to an appropriate location, e.g., the clinical analyzer or a waste receptacle, based upon results of the evaluation.
The following terms used in this application shall have the following meaning:
xe2x80x9cNeat Serum Samplexe2x80x9d shall mean undiluted serum or plasma.
xe2x80x9cPrimary Collection Tubexe2x80x9d shall mean a blood collection tube used to collect blood from a patient. A suitable blood collection tube is manufactured by Becton Dickinson, located in Franklin Lakes, N.J.
xe2x80x9cSerum Variablesxe2x80x9d shall mean and include hemolysis, icterus, lipemia and other variables, which may affect the accuracy of the results of the clinical analyzer.
xe2x80x9cInterferantxe2x80x9d shall mean and include any of the serum variables, any disease condition and/or any variable which may affect the interpretation of the results of the clinical analyzer and/or be of interest to the doctor or patient.
xe2x80x9cHemolytic indexxe2x80x9d shall mean the grade given to a particular sample based upon the estimated content of hemolysis present in the sample. Generally, the grading scale for visual observation ranges from zero through four (0-4). Zero represents substantially no hemolysis while four represents significant hemolysis. Alternately, the scale could be 0-10, 0-20, A-F or some other range.
xe2x80x9cIcteric indexxe2x80x9d shall mean the grade given to a particular sample based upon the estimated content of icterus present in the sample. Generally, the grading scale for visual observation ranges from zero through four (0-4). Similarly, zero represents substantially no icterus, while four represents significant presence of icterus. Alternately, the scale could be 0-10, 0-20, A-F or some other range.
xe2x80x9cLipemic indexxe2x80x9d shall mean the grade given to a particular sample based upon the estimated content of lipemia present in the sample. Generally, the grading scale for visual observation ranges from zero through four (0-4). Similarly, zero represents substantially no lipemia, while four represents significant presence of lipemia. Alternately, the scale could be 0-10, 0-20, A-F or some other range.
xe2x80x9cSerum Indicesxe2x80x9d shall mean and include the hemolytic index, the icteric index and the lipemic index.
xe2x80x9cPredetermined Valuexe2x80x9d shall mean a value for the hemolytic index, the icteric index or the lipemic index at which the integrity of the sample for testing may be considered to be compromised. The predetermined value varies according to the scale of the serum indices, which of the serum indices is in question and the tests to be performed by the clinical analyzer or other device. For example, if the hemolytic index is rated on a scale of 0-4, a hemolytic index of 3 could be considered to compromise the sample for some tests. Thus, the predetermined value in this example would be 3. Alternately, a reading of 2 on a scale of 0-4 for the icteric index could be unacceptable in some instances. Thus, for this example, the predetermined value is 2.
xe2x80x9cSpectophotometric analysisxe2x80x9d shall mean and include measuring optical absorbence and/or reflectance, a turbidimetric analysis, a nephelometric analysis, and/or light scatter analysis at any angle or collection of angles.
In a screening test, the optical probe can determine whether an interferant is present in the serum sample. Further, the optical probe can establish one or more of the hemolytic index, the icteric index and the lipemic index of the sample. This allows the laboratory to determine whether the sample is suitable for testing with the clinical analyzer and allows the results from the clinical analyzer to be properly evaluated. With the present invention, the serum variables and a serum indices are evaluated without consuming or altering the sample.
In a volume test, the optical probe evaluates the amount of sample available in the sample container. This allows the laboratory to properly allocate the sample for additional testing. For a volume test, the optical probe is positioned near the sample and is used to determine the location of an upper sample surface of the sample in the sample container. With the location of the sample surface and the shape of the container, the volume of sample in the sample container can be evaluated. Again, the sample is evaluated in the storage container, prior to being removed from the storage container.
Also, the method can include the step of transferring the sample to another location based upon the results of the preliminary tests on the sample. For example, the sample container and sample can be transferred to a waste receptacle, if one of the serum indices is above the predetermined value or the sample container and sample can be transferred to a clinical analyzer for additional testing or a sample splitter if all of the serum indices are below the predetermined value.
The invention is also directed to a device for performing a preliminary test on the sample. The device includes an optical probe having a probe body, a collector, and a detector. A probe tip of the probe body is positioned near the sample container. The collector receives information about the sample. This information is transferred to the detector, which performs the preliminary tests on the sample based upon information received by the collector.
It is important to recognize that with the present invention, the integrity of a neat serum sample can be tested within a primary collection tube, without using a laboratory worker and without removing the neat serum sample from the primary collection tube. Additionally, the present invention quickly and accurately determines the level of the serum indices, without consuming any of the neat serum sample and without adversely effecting the integrity of the neat serum sample. Furthermore, the optical probe can measure the amount of sample in the storage container to ensure that enough sample exists for testing before transferring the sample to the clinical analyzer.